Lock is null. Nothing to release

OpenSearch
1

Versions: 3.2.0

Two days ago we got alerts about fluent-bit got oom killed.
While checking logs everywhere trying to find the reason I found the error log message in opensearch during the issue time frame on two of three nodes:

Lock is null. Nothing to release.

This message repeated 313 times during 30 minutes.
I can’t find any other issues in the logs that might explain what’s happening so this message is telling me nothing.

What does this message actually telling me about our opensearch cluster?

2

@pitch Could you share the original full entry with that message?

How did you deploy your cluster and what is your OS nodes resource configuration?

3

full log entry:

[2025-10-15T08:46:46,847][ERROR][o.o.a.c.l.LockService ] [obs-logdb-04] Lock is null. Nothing to release.

the cluster is deployed on three vm nodes with one node as master and ingest

24 GB mem on master/ingest node
20 GB on the other two
6 cpu on all nodes

4

The message is coming from here alerting/core/src/main/kotlin/org/opensearch/alerting/core/lock/LockService.kt at main · opensearch-project/alerting · GitHub, but I don’t think there’s enough info to help debugging the OOM error. Is there any more information you can provide?

5

@pitch I understand all your nodes have master, ingest and data roles?

Was there any significant ingest increase during that time?

Which plugins do you use?

6

Thank you @cwperks for that information.
Why does that error occur? We’ve seen the error occasionally that’s why my primary question. I suspect we have a network issue and that’s probably the reason we got the oom kill of fluent-bit.

7
  • Yes
  • We got ingest decrease during that time.

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